GPPS (General Purpose Polystyrene)

Also called: General purpose polystyrene, crystal polystyrene, PS, resin code 6

GPPS (general purpose polystyrene) is clear, rigid and brittle polystyrene used for transparent packaging, disposables and housewares.

General purpose polystyrene (GPPS), also called crystal polystyrene, is unmodified polystyrene. It is glass-clear, rigid, easy to mould and fairly brittle. Its density is about 1.04-1.05 g/cm3, and it carries resin identification code 6. Expanded polystyrene (EPS foam) is a separate form of the same polymer.

Recycled forms traded

• Clear moulding rejects and runners from cosmetic, stationery and houseware moulders.
• Disposable cups, cutlery and clear containers, usually mixed with HIPS.
• PS regrind and recycled granules, often in clear, mixed or black.

Why it matters when buying recycled plastic

• If clarity matters, buy only sorted clear post-industrial GPPS; any HIPS or colour turns it hazy.
• GPPS is brittle, so regrind can carry many fines. Ask for dust levels and particle size.
• Check MFI and contamination on a sample before you commit to a full load.

Common uses

Transparent containers, cosmetic packaging, CD-type cases, stationery, houseware, light diffusers and blending with HIPS for injection moulding.

Because polystyrene is brittle and easily mixed with other styrenics, sorted single-source lots are usually worth the extra effort for quality-critical parts.